Electronic musical instrument with frequency-deviated pedal tone signal

ABSTRACT

In an electronic musical instrument, a tone signal for the pedal keyboard is obtained by frequency-dividing the manual tone signal. The pedal tone signal thus obtained is passed through a frequency shifter to become a slightly frequency-deviated signal whose frequency is not an exact integral submultiple of the frequency of the manual tone signal. In this instrument, concurrent sounding of the pedal tone and the manual tone brings out a beat as in an instrument having tone generators of an individual oscillating system.

United States Patent [191 Suzuki July 30, 1974 [5 ELECTRONIC MUSICALINSTRUMENT 2,892,372 6/1959 Bauer 84/1.25 WITH FREQUENCY DEVIATED PEDAL3,098,888 7/1963 Tomcik 84/1.17 TONE SIGNAL 3,488,515 1/1970 Hiyoshl84/101 X 3,535,969 10/1970 Bunger 84/D1G. ll [75] lnventor: AkihisaSuzuki, Kamimura, Japan 3,598,892 8/1971 Yamashita 84/].01 3,619,469111971 Ad h' 84 1.17 [73] Assignee: Nippon Gakki Seizo Kabushiki M lKaisha, Shizuoka-ken, Japan 22 F1 d: O t. 17, 1972 PrimaryExaminer-Richard B. Wilkinson 1 c Assistant Examiner-Stanley J.Witkowski 1 1 pp 298,357 Attorney, Agent, or Firm-Holman & Stern RelatedUS. Application Data [63] Continuation-impart of Ser. No. 113,249, Feb.8,

1971, abandoned. 57 ABSTRACT [30] Foreign Application Priority Data Inan electronic musical instrument, a tone signal for Feb. 10, 1970 Japan45-12784 the pedal keyboard is obtained by frequency-dividing Feb. 26,1970 Japan 45-19153 the ma ual tone signal, The pedal tone signal thus0btained is passed through a frequency shifter to become [52] US. Cl.84/117, 84/124 3 lightly frequency-deviated signal whose frequency is[51] Int. Cl. GlOh l/04 t an exa t integral ubmultiple of the frequencyof Field 01 Search 122-125, the manual tone signal. In this instrument,concurrent DIG. 1 1, 25 sounding of the pedal tone and the manual tonebrings out a beat as in an instrument having tone generators [56] efeenc Cited of an individual oscillating system.

UNITED STATES PATENTS 2,879,683 3/1959 Martin 84/124 4 Claims, 10Drawing Figures PHASE SHIFTER MODULATOR 0 PS 1 M1 l fa f f0 --Af c LATORS b FILTER *1 I Af d \ EXTRENELY LOW FREQUENCY f0 0 OSCILLATOR PATENTEU3.826.859

SHEET 1 0f 3 PHASE SHIFTER MODULATOR PS MI I f0 1 fc-Af s I C MODULATORFILTER Af d.

EXTREMELY LOW FREQUENCY f Af LFO OSCILLATOR UK UKT LOwER KEYBOARD"LONE-COLORING CIRCUIT AMPLIFIER s LK 'LKT A SOUND LOWER KEYBOARD PEDALTONE- SOURCE SWITCHING CIRCUIT COLORING CIRCUIT SP CIRCUIT PM D PK PKTFS IEIIBIR BEAR ERA-m BARKER- CIRCUIT CIRCUIT CIRCUIT DIvIOE F I G. 3

' UPPER KEYBOARD TO E-COLORING CIRCUIT UK UKT UPPER KEYBOARD LOWERKEYBOARD SWITCHING CIRCUIT TONBCOLORING C'RCUIT AMPLIFIER I S IL IILK |LLK-H A LOWER KEYBOARD gaggg; SWITCHING CIRCUIT EE L SP PRIORITYFREQUENCY IFREQUENCY E|E; %Al|J lTTONE-COLORING MEMORY -DIvIsION CIRCUITC|RCU|T QYg QN PATENTEU JUL30I974 UPPER KEYBOARD SWITCHING CIRCUIT sum 2or 3 UPPER KEYBOARD TONE -COLOR|NG CIRCUIT UK UKT LOWER KEYBOARD LOWERKEYBOARD TONE-COLORING AMPLIFIER SWITCHING CIRCUIT /CIRCU|T s L K T L KTA SOUND SOURCE ERIQS PEDAL SWFTCHING SP CIRCUIT CIRCUIT /C|RCU|T PM D PKFS EEEEW FREQUENCY CIRCUIT DEVIATION DIVICE F l G. 5

PHASE SHIFTER MODULATOR U PS Ml FILTER 9 h OUT 8 b C F MODULATOR M2 d flL F O T EXTREMELY LOW FREQUENCY OSCILLATOR PIIIENIEIIIIIIB 3826.859

SHEET 3 BF 3 F I G. 6

UPPER KEYBOARD UFBPER KEYBOARD SWITCHING CIRCUIT [TONE-COLORING CIRCUITU K U K T LOWER KEYBOARD LOWER KEYBOARD 0| QR SWITCHING CIRCUIT 5%,?AM/PUF'ER S L K I L K T A SOUND FREQUENCY- SOURCE DIVISION FREQUENCY- 5PCIRCUIT C|RCU|T /DEVIAT|ON DIVICE PM D FS P K K I-2 \PEDAL SWITCHINGCIRCUIT F l G. 7 LflO 0 8. E 1? CC C OONTROL VOLTAGE F l G. 9

6 CC# C 2 O E CONTROLLING \L 1 l 1 L VOLTAGE our ELECTRONIC MUSICALINSTRUMENT WITH FREQUENCY-DEVIATED PEDAL TONE SIGNAL This is acontinuation-in-part of application Ser. No. 113,249, filed on Feb. 8,1971, which is now abandoned.

BACKGROUND OF THE INVENTION Heretofore, in electronic musicalinstruments, there has been an independent pedal tone generator systemwhich is provided with tone generators especially for pedal tones otherthan manual tones; and in a second alternative system a frequencydivision tone generator system is provided with tone generators incommon for manual tones and pedal tones wherein a desired signal isselected and memorized and then is frequencydivided down to a pedaltone.

In the former system, the pedal tone signals are produced by their owntone generators separated from those for the manual tones. Therefore,when the manual tone and the pedal tone are sounded at the same time, aslight difference of the frequencies between these tone signals producesa natural beat sound, whereby a musical performance can be attained insuch a way that the manual tone comes out prominently, and the pedaltone is increased in tone heaviness (richness as a base tone).Therefore, the former system is very effective in tone quality, but hasa drawback in that it is hard to stabilize an oscillating frequency atsuch a low frequency region as an individual tone signal oscillator.

On the other hand, the latter system which is utilized for most ofelectronic organs has advantages in that it is stable in frequency andlow in production cost, but however has disadvantages that the beatsound such as can be found in the individual tone generator systemcannot be obtained, because the manual tone and the pedal tone arealways in relationship of an exact harmonic.

SUMMARY OF THE INVENTION It is accordingly a primary object of thepresent invention to provide a novel organization of an electronicmusical instrument in which a natural beat sound is produced between amanual tone and a pedal tone, whereby all of the above describeddrawbacks of the conventional devices can be eliminated.

Another object of the present invention is to provide an electronicmusical instrument of a frequencydivision tone generator system, inwhich, when a pedal tone and a manual tone are produced at the sametime, a beat sound effect which is rich in natural sound sensation as isfound in an electronic musical instrument having an individual tone.generator system, can be obtained.

A further object of the present invention is to provide an electronicmusical instrument of a frequencydivision tone generator system, inwhich a frequency shifter adapted to slightly deviate a pedal tonefrequency is provided in a pedal sound system and a voltage control typeoscillator in the frequency shifter is controlled by a voltage furnishedfrom a memorizing selector circuit whereby the frequency deviation iscontrolled in response to a tone pitch of the pedal tone.

A still further object of the present invention is to provide a novelelectronic musical instrument which can operate in a purely electronicmanner and is simple in construction and economical in production.

The foregoing objects and other objects as well as the characteristicfeatures of the invention will become more apparent from the followingdetailed description and the appended claims when read in conjunctionwith the accompanying drawings, in which like parts are designated bylike reference symbols.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawings:

FIG. 1 is a block diagram showing an example of the frequency shifteremployed in a pedal tone generating circuitry of an electronic musicalinstrument, according to the present invention;

FIG. 2 is a block diagram illustrating one embodiment of the electronicmusical instrument of the present invention;

FIG. 3 is a block diagram showing another embodiment of the electronicmusical instrument according to the present invention;

FIG. 4 is a block diagram showing a further embodiment of the electronicmusical instrument according to the present invention;

FIG. 5 is a block diagram illustraing an example of the frequencyshifter used in the electronic musical instrument shown in FIG. 4;

FIG. 6 is a block diagram showing a still further embodiment of theelectronic musical instrument according to the present invention;

FIG. 7 is a graphic diagram showing a characteristic of a controlvoltage derived from a memorizing selector with respect to note names;

FIG. 7a illustrates by way of example a circuit for producing an outputas shown in FIG. 7;

FIG. 8 is a graphic diagram illustrating a characteristic of controlvoltage VS. oscillation frequency of an extremely low frequencyoscillator used in the frequency shifter shown in FIG. 5; and

FIG. 9 is a graphic diagram showing a pedal tone frequencycharacteristic with respect to note names.

DETAILED DESCRIPTION OF THE INVENTION With reference now to theaccompanying drawings and more particularly to FIGS. 2 and 3,embodiments of the electronic organ according to the present inventionare illustrated in the form of a block diagram. In these figures, thearrangement of parts other than a frequency shifter FS shows onearrangement of a conventional electronic organ having afrequency-division tone generator system. The embodiment according tothe present invention comprises a sound source circuit S (including tonegenerators), an upper keyboard switching circuit UK, an upper keyboardtone-coloring circuit UKT, a lower keyboard switching circuit LK, alower keyboard tone-coloring circuit LKT, a memorizing selector circuitPM which serves to select, in association with the pedal key depression,one tone signal from the sound source circuit S and memorizingly connectit to the succeeding circuit until another pedal is next depressed (thiscan be constructed mechanically by a lock-and-release type push buttonswitch or electrically by a circuit described in the US. Pat. No.

3,488,515 to Hiyoshi), a frequency-division circuit D which serves tofrequency-divide a selected tone signal from the memorizing selectorcircuit PM down to a desired frequency, a pedal switching circuit PK, apedal tone-coloring circuit PKT, the frequency shifter FS which isadapted to shift (deviate) the frequency of the pedal tone signal by asmuch as a frequency which is sufficiently lower than that of the pedaltone signal, an amplifier A, and a loudspeaker SP.

Now, if parts other than the frequency shifter F8 are taken intoconsideration, the combination of the parts is completely similar tothat of the conventional electronic organ having the frequency-divisiontone generator system, and musical tone signals from the sound sourcesare properly tone-colored by the upper keyboard tone-coloring circuitUKT and the lower keyboard tone-coloring circuit LKT after having passedthrough the upper keyboard switching circuit UK and the lower keyboardswitching circuit LK, respectively. Then, the thus tone-colored signalis amplified in the amplifier A and converted into a sound through theloudspeaker SP. In a parallel circuit, after a musical tone signalthrough the memorizing selector circuit PM has been frequency-divided bythe frequency-divider D, it is keyed by the pedal switching circuit PK,properly tone-colored through the pedal tone-coloring circuit PKT, andin the absence of a frequency deviation device then, the thustone-colored signal is amplified by the amplifier A and furtherconverted into a sound by the loudspeaker SP. In this case (without afrequency shifter), if both the pedal switching circuit PK and the upperkeyboard switching circuit UK or the lower keyboard switching circuit LKare rendered conductive at the same time, both a pedal sound and anupper keyboard sound or a lower keyboard sound are simultaneouslyproduced. Since these two sounds are originated from the same musicaltone signal, they are the same in tone-pitch or are in the relationshipof exact harmonics, as a result of which only a coupler effect isobtained at best, but a beat sound as obtainable in the case of anindividual tone generator system cannot be obtained, and accordingly itis inevitable for the obtained sound to be rather monotonous.

In order to overcome the above drawbacks, such an arrangement is made inthe present invention that a natural beat sound is obtained between thepedal sound and the upper or lower keyboard sound by slightly deviatingthe frequency of the pedal sound. A device by which the frequency of themusical tone signal is thus slightly deviated, is represented byreference symbol F in FIGS. 2 and 3, and the device FS is illustrated ingreater detail in the form of a block diagram in FIG. 1.

Now, with reference to FIG. 1, a musical tone signal from a musicalsound source S (the signal generally comprises a plural frequencycomponents and moreover it varies from time to time in accordance withthe progression of the musical performance, but, for the convenience ofexplanation in this specification, the signal is represented by a singlefrequency of f,,Hz) is converted by a phase-difference network PS intotwo musical tone signals which are 90 phase shifted in phase from eachother. Further, two signals (as carrier waves) furnished from anextremely low frequency oscillator LFO and having a frequency Afsufficiently lower than that of the musical tone signal and shifted by90 in phase from each other are respectively amplirude-modulated withthe above mentioned phasedifferent tone signals (as modulating waves) inmodulators M and M Then the modulated output signals from the modulatorsM. and M are mixed together and an unnecessary extremely low frequencysignal component is eliminated by a high-pass filter F thereby to obtaina signal having a frequency f,, :L Af, and further only a signal havinga frequency f,, Af is finally taken out.

The above processes can be shown by the following formulas:

Signal at a terminal a a cos w t (w 21rf,,),

Signal at a terminal I) a sin w t (w 2'n-f,,)

Signal at a terminal c A cos pt 2 ZrrAf) Signal at a terminal d A sin pt(p 21rAf) where a and A represent the signal amplitudes, respectively.

The signal at the terminal a and c leads the signal at the terminal band d by 90 in phase, respectively, accordingly;

M output: A(l m cos wt) cos pt M output: A(l m sin wt) sin pt where ma/A (modulation factor). Therefore, a mixed signal will be:

M +M =2 VTA cos (pt-1r/4)+mA cos (wp)t.

Accordingly, when Af component is eliminated by means of the filter, theresultant output will be mA cos (0) p)t, and a signal having a frequencyf,, Af that is lower by as much as a frequency Af than the frequency f,,of the musical sound signal, can be obtained.

As a result, a pedal tone signal lower by as much as Af than an originalpedal tone signal is obtained by inserting such a frequency shifter in apedal tone generating circuitry, whereby a beat sound whose frequency isAf can be obtained by simultaneously producing a pedal sound and amanual sound.

In the embodiment shown in FIG. 2, the higher harmonies of the pedalsound are also deviated in frequency by as much as Af. If this deviatedquantity is represented by a ratio of frequency deviation, for instancein percent, the ratio becomes rather small for higher harmonics, andtherefore a beat effect cannot be very pronounced as far as higherharmonics are concerned.

In order to obviate this disadvantage another circuit shown in FIG. 3 isprovided,.in which the frequency shifter FS is provided immediatelybefore the pedal switching circuit. In this circuit, only a fundamentalcomponent is taken out from the memorizing selector circuit PM and isfed to the frequency shifter FS, thereby to be deviated in frequency byas much as Af, and then the waveform of the fundamental frequency signalis converted by the tone-coloring circuit PKT into a more complicatedwaveform, thereby to obtain desired higher harmonics. In this case, boththe fundamental and higher harmonics of the pedal tone are deviated infrequency to the same extent in terms of percent, and when the manualkeyboard sound and the pedal sound are simultaneously produced, the samebeat effect as in the individual tone generator system can be obtained.

FIG. 4 illustrates a further embodiment of the present invention, inwhich a frequency shifter FS serves to deviate its input signalfrequency f}, into its output signal frequency f,, A f (where Af is anextremely low frequency of 0.5 Hz to 10 Hz), and the extremely lowfrequency is varied by a controlling voltage furnished from a memorizingselector circuit PM. i

FIG. 5 shows an embodiment of the frequency shifter FS shown in FIG. 4.The circuit of this embodiment comprises a phase-difference network PSwherein a musical tone signal is supplied to its input and two musicalsound signals differing by 90 in phase within a frequency range for useare produced at the output, a voltage control type variable extremelylowfrequency oscillator LFO adapted to generate two signals having afrequency (0.5 Hz) which is extremely lower than that of a musical tonesignal and which are different by 90 in phase from each other,amplitude-modulators M and M which serve to amplitude-modulate theextremely low frequency signals (as carrier waves) furnished throughterminals 0 and d with the musical sound signals (as modulating waves)passing through terminals a and b respectively, and a high-pass filter Fadapted to cut off an oscillating frequency component furnished from theextremely low frequency oscillator LFO.

Now, assuming that the phase of the musical tone signal at the outputterminal b of the phase-difference network PS lags by 90 behind that atthe output terminal a and the phase of a signal (carrier wave) to bemodulated at the output terminal d lags by 90 behind that at the outputterminal c, each of the signals at the terminals a, b, c and d isrepresented by the following formulas respectively:

Therefore, when the signal at the terminal c is amplitude-modulated withthe musical sound signal at the terminal a in the amplitude-modulator Man output of the amplitude modulator M, is represented by a formulabelow:

M output A cos pt (I m cos out) A cos pt (mA/2) cos (w +p)t (mA/2) cos(m p)t, where m Ka means the amplitude modulation factor (K is themodulation sensitivity).

In the same way as described above, when the signal at the terminal d isamplitude-modulated with the musical sound signal at the terminal in theamplitudemodulator M an output of the amplitude-modulator M isrepresented by a formula below:

M output A sin pt (I m sin wt) A sin pt (mA/2) cos (w +p)t (mA/2) cos((0 -p)t where m Ka means the amplitude modulation factor (K is themodulation sensitivity). Then, those outputs from the amplitudemodulators M and M are combined at a terminal g into a signal shown bythe following formula:

Signal at the terminal g A (cos pt sin pt) mA cos (w p)t Successively,Af component is removed from this signal by means of the filter F, andas a result a signal represented by the formula; mA cos (w p)! isobtained at the output terminal h of the filter F. The angular frequencyof this signal is lower by as much as p(Af in frequency) than that ofthe original musical tone signal at a terminal (1,. In this case, theextremely low frequency oscillating circuit LFO is one whose frequencyis varied by a control voltage applied thereto.

The relationship between a controlling voltage applied to a frequencycontrol terminal T of the extremely low frequency variable frequencyoscillator LPG and an oscillating frequency thereof is, for instance, asshown in FIG. 8 and the oscillating frequency becomes higher withincreasing controlling voltage. Therefore, when a voltage shown in FIG.7 is produced in the memorizing selector circuit PM by an additionalcircuit therein (as exemplarily illustrated in FIG. 7a) and the thusproduced voltage is fed to the control ter minal T of the variablefrequency oscillator LFO, a frequency deviation can be obtained inresponse to a tonepitch (note name) of the pedal sound and further thecharacteristic of the pedal sound frequency can be made, for instance,as shown in FIG. 9 to respond to each of tone-pitches (note names).

In embodiments described above, although the frequency of the higherharmonics is also deviated by as much as -Af, the deviated quantitiesare smaller in ratio as compared with the fundamental when representedin percent (ratio of frequency deviation) and therefore would not beundesirable in an actual use.

FIG. 6 illustrates a still further embodiment of the present invention.FIG. 6 is different from FIG. 4 in that the frequency deviation circuitFS is arranged between the frequency-division circuit D and the pedalswitching circuit and tone-coloring circuit DK. Although the operationof this embodiment is substantially the same as that of FIG. 4, only thefundamental component of the output signal of the memorizing selectorcircuit PM is frequency-deviated by as much as Af in the frequencydeviator device FS and then, desired higher harmonics are obtained inthe pedal tone keyer and tone-coloring circuit PK. As a result, theoperation of this embodiment is different from that of FIG. 4 in thatboth the fundamental wave component and the higher harmonic wavecomponents are deviated by the same percentage value.

While a few embodiments of the present invention have been illustratedand described in detail, it is particularly understood that the presentinvention is not limited thereto or thereby.

I claim:

1. An electronic musical instrument producing an accoustic beat effectby generating a frequency deviated pedal tone signal, comprising:

a musical sound signal source for generating tone signals for manualtones and pedal tones in a frequency division tone generator system;

a switching circuit for a manual keyboard having manual keys andconnected to said musical sound signal source for switching tone signalstherefrom;

a manual keyboard tone-coloring circuit connected to said manualkeyboard switching circuit for tonecoloring the switched tone signalsand providing a first output signal representative thereof;

memorizing selector means operated by a set of pedal keys and connectedto said musical sound signal source for selecting a tone signal fromsaid source upon depression of one of said pedal keys, and memorizingsaid selected tone signal until another of said pedal keys is depressed;

frequency dividing means connected to said memorizing selector means forfrequency-dividing said selected tone signal and providing an outputfrequency therefrom;

a pedal switching circuit operated by said pedal keys and connected tosaid frequency dividing means for switching said output frequency fromsaid frequency dividing means;

a pedal tone-coloring circuit connected to said pedal switching circuitfor tone-coloring said output frequency switched thereform and providinga second output signal representative thereof;

means defining an interconnecting point connecting said first outputsignal from said manual keyboard tone-coloring circuit with said secondoutput signal from said pedal tone-coloring circuit;

and frequency deviation means connected in series between said frequencydividing means and said interconnecting point for reducing said outputfrequency of said frequency dividing means by a constant predeterminedfrequency so that when said first and second output signals are combinedat said interconnecting point a combined signal is produced having anacoustic beat effect.

2. An electronic musical instrument as claimed in claim 1, wherein saidfrequency deviation means includes a low frequency oscillator, andwherein said memorizing selector means includes means furnishing acontrolling voltage connected to alter an output frequency of said lowfrequency oscillator.

3. An electronic musical instrument as claimed in claim 1 wherein saidfrequency deviation means is connected in series between said frequencydividing means and said pedal switching circuit.

4. An electronic musical instrument as claimed in claim 1 wherein saidfrequency deviation means is connected in series between said pedaltone-coloring circuit and said interconnecting point.

1. An electronic musical instrument producing an accoustic beat effect by generating a frequency deviated pedal tone signal, comprising: a musical sound signal source for generating tone signals for manual tones and pedal tones in a frequency division tone generator system; a switching circuit for a manual keyboard having manual keys and connected to said musical sound signal source for switching tone signals therefrom; a manual keyboard tone-coloring circuit connected to said manual keyboard switching circuit for tone-coloring the switched tone signals and providing a first output signal representative thereof; memorizing selector means operated by a set of pedal keys and connected to said musical sound signal source for selecting a tone signal from said source upon depression of one of said pedal keys, and memorizing said selected tone signal until another of said pedal keys is depressed; frequency dividing means connected to said memorizing selector means for frequency-dividing said selected tone signal and providing an output frequency therefrom; a pedal switching circuit operated by said pedal keys and connected to said frequency dividing means for switching said output frequency from said frequency dividing means; a pedal tone-coloring circuit connected to said pedal switching circuit for tone-coloring said output frequency switched thereform and providing a second output signal representative thereof; means defining an interconnecting point connecting said first output signal from said manual keyboard tone-coloring circuit with said second output signal from said pedal tone-coloring circuit; and frequency deviation means connected in series between said frequency dividing means and said interconnecting point for reducing said output frequency of said frequency dividing means by a constant predetermined frequency so that when said first and second output signals are combined at said interconnecting point a combined signal is produced having an acoustic beat effect.
 2. An electronic musical instrument as claimed in claim 1, wherein said frequency deviation means includes a low frequency oscillator, and wherein said memorizing selector means includes means furnishing a controlling voltage connected to alter an output frequency of said low frequency oscillator.
 3. An electronic musical instrument as claimed in claim 1 wherein said frequency deviation means is connected in series between said frequency dividing means and said pedal switching circuit.
 4. An electronic musical instrument as claimed in claim 1 wherein said frequency deviation means is connected in series between said pedal tone-coloring circuit and said interconnecting point. 